Circuit-interrupting system.



L. W. CHUBB.

CIRCUIT INTERRUPTING SYSTEM.

APPLICATION FILED JULY 5, m7.

1,287,233. Patented M010, 1918.

WITNESSES: INVENTOR f Lew/3. W C/iubb W 4 ATTORNEY ,UEITE STATES PATENT OFFICE.

LEWIsw. GHUBB, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR. To WESTINGHOUSE nnnc'rnroa MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA.

CIRUIT-INTERRUPTING SYSTEM.

T0 all whom-it may concern Be. it known that,I,' LnW1 s Cum n, a citizen of the United States, and, a resident of Pittsburgh, in the ,countyf'of Allegheny and State. of Pennsylvania, have invented a new. and :useful Improvement in Circuit-Interrupting. Systems, of which l the if ollowing a .One object. of lny invention is to- ..proi i( le ',a circuit. interrupter of the above indicated character ,that shall .have means for'energizingits trip; coil when a current Wavehaving a predetermined eiiective myalue passes throughits zermyalue topermit the circuit interrupter to ;be so timed inits floperation that it 'wvilLhecpened at-,a time correspond- Ting to aipredetermined numberof half cycles from the time its trip coil-isenergized.

- Another object of my invention is to provide means for a circuit interrupter of the above indicated character that .shall be adapted! to so .peak the potentialavvave impressed across the trip .coil circuitatits unaxinium valueithat the;trip: coil-will be energized only at-themaximum value of the potential: wave- -impressed thereacross and, consequently, at the zero-value of. the current xvave traversing: the: circuit.

Mv' copending application Serial No.

nant or tuneddevicethat is connected .to. a main. circuit for so controlling. thetrlp coil of a circuit interrupter that it will be energizeda sufiicient-time interval-before the inopen only when no current traverses the same. The-trip coil is connectedv in series relation to'a spark gap and the circuit, thus constituted, is connectediacross the condensive element of'the resonant circuit. -Thus, Iwhenithe potential across-:the-trip coil circuit that corresponds to the break-down value Of-i'thfi spark gap is reached andthis wave willgbepassing throughiitszero value,

and, consequently; the trip coil .wvillbe energized: when the current: wave passes through Specification of Letters Patent.

cuit 2 comprising conductors? and 4. .clrcuit interrupter. 5 is connected lnclrcult Patented Dec. '10, 1918.

Application filed July 5, 1917, vSerial No. 12"8,6 74.

its zero value. Means is provided for so advancing the phase-angular relation between the potential of the condensive element of the resonant circuit and the remain portion of the resonant circuit that the maximum value of the voltage Wave across the condensive element of :the circuit occurre an interval of time before the zero value in the other element of the circuit that corresponded tothe time required for U the circuitintcrrupter'to operate.

Since the resonant current throughthe resonant circuit of the above indicated devicebuilds up with a logarithmic increment,

it is} likely that thesparlc voltage of the spark gap will be higher than'that reached in one cycle of this increasing voltage. Thus, thespark gap will not break down beforethebeak ormaximum value ofthe succeecling'cycle. In view of this, I provide anlimpulse transformer having a normally saturated corc rncmloer. The transformer is connected betweeuthe main circuit and the circuit comprising the spark gap' and the ,trip coil. The sudden change of flux at the,

zero valuein the, current in thejmain circuit nduces an mpulse voltage and since this I impulse voltage is superposed upon the main voltage across vthe spark gap, the voltage ,acrossthe spark gap will break .downat its maximum value only. That 'is the inaxi mum value of the current flowing during at least one cycle corresponds to the breakvdown,value of thesp'ark gap. The time of operation oflthe interrupter isso adjusted, that it will operate to 'open the circuit in a .time that correspondslto an integral num- '.ber .of-lialf cycles after the spark gap breaks down, thus causing the circuit to be opened at zero'va-lue of the current wave under all conditions.-

In the.accompanying.drawings Figure 1 1s a d1agrammat1c ,Vlcmofan electric circuit embodying my invention Fig. 2 is a diagram illustrating the voltage peaks induced by the transformer shown in Fig. l,,and

Fig. 3 is a diagram illustrating the change in the potential wave that is eflectedby the use of myinvention. v

Agenerator 1 suppliescurrentto a cirwith the conductor 3 of .the circuit Zfor the circuit interrupter 5 is provided with a trip coil 6 that is energized through a series transformer 7 from the circuit 2. A second interrupter 8 is connected in series with a non-inductive resistor 9 and the primary winding 10 of a transformer 11 and the circuit, thus constituted; is connected in shunt relation to the circuit interrupter 5. While I have shown the circuit interrupters 5 and 8 as connected in only one conductor of the circuit 2, it will, of course, be understood that both conductors of the circuit may be protected in the same manner.

A series resonant circuit 12 comprising a reactor 13, a condenser 14 and a resistor 15 is connected in shunt relation to the resistor 9. A trip coil 16 is connectedinseries relation to a spark gap 17 and the secondary .winding 18 of-the transformer 11 and the circuit, thus constituted, is connected in shunt relation to the condenser 14.

The transformer 11 is provided with a magnetizable core, member 19 that is nor mally saturated. The primary winding 10 of the transformer 11 has a relatively few number of turns and the secondary winding 18 has a relatively large number of turns.

When an abnormal current traverses the conductors 3 and 4, sufficient current is induced in the transformer 7 and, consequently, the trip coil 6 to trip the circuit interrupter 5 which, on opening, causes the current to traverse the resistor 9, the windinglO of the transformer 11 and the interrupter 8. The resistor 9 andlthe winding 10 tend to reduce the current and since the re actor 13, condenser 14 andresistor 15 are of such values that they"constitute a resonant circuit for the normal frequency of the generator 1, the resonant current through the circuit 12 will build-up with a logarithmic increment. H y

If the voltage required'to break down the spark gap 17 is higher than that reached in any one cycle, as, for instance, the cycle indicated at, 20 in Fig; 3 of the drawings, it will not spark but may'break down at the point 21 on the succeeding cycle 22 before the maximum value of the cycle 22 is reached. That is, the broken line- 23 of the diagram shown in 3 of the drawings I represents the break-down voltage 1 of the spark gap 17 and thus illustrates a'condition under which the trip coil 16 ,will be energized at a value'other than its maximum such as the transformer 11', that automatically induces an impulse of voltage when the mam current passes through its zero -voltage to be superposed on the condenser voltage when the current traversing the resistor 9 and the interrupter 8 is zero 'and'reversing. The diagram in Fig. 2 illustrates the impulse voltage that is induced in the secondary winding. 18 of the transformer 11.

Since the secondary Winding 18 of the transformer 11 is connected in series with the trip coil 16 and the spark gap 17, the impulse voltageis added to the main voltage across the condenser 14 and thus the voltage across the condenser 14 will assume values shown in Fig. 3 when the same is building up.

through the cycle, as indicated at 20, the

spark gap 17 will breakdown and the trip coil 16 will be so energized as to'trip the circuit interrupter 8. The time required I' for the interrupter 8 to open after its trip coil'16 is energized corresponds to the time of an integral numberof half cycles from the break down of the spark gap 17. Thus, since the break down of the spark gap 17 occurs at the maximum value of the potential across the condenser 14 and, consequently, at' the zero value of the current traversing the interrupter 8, and since the interrupter 8 is opened in a time that is an integral number of'the half cycles from the time that the spark gap 17 breaks down, it is assured that the circuit is interrupted at the zero value only of the current wave traversing the-same.

While I have described my invention with respect to the tripping of a circuit interrupter when the instantaneous value of currentit'raversing it is zero, I do not limit my inventionto the particular arrangement illustrated as many modifications may be used'without departing from the spirit and scope of the invention as set forth In the appended claims.

-= I claim as my invention 1. In'an electric circuit,the combination with a circuit interrupter, a series-resonant circuit and a trip coil connected across a portion of the resonant circuit and adapted to be energized under predetermined conditionsof the current traversing the electric circuit, of means for inducing an impulse voltage on the voltage wave across a portion of the resonant circuit as its maximum value.

2. In an electric circuit, the combination with a circuit interrupter, a trip coil therefor and means for energizing the trip coil under predetermined conditions of current in the circuit, of means for so peaking the voltage wave inthe trip coil circuit that the trip coil is energized only at the zero value of the current wave in the electric circuit.

3. The combination with an alternatingcurrent circuit, a circuit interrupter, a trip coil and means for energizing the trip coil when a predetermined maximum voltage is impressed thereacross, of means connected in the circuit for peaking the voltage wave in the trip coil circuit at 1ts maximum value only.

4:. In an electric circuit, the combination with two parallel-connected circuit interrupters, and means for trippin one interrupter under predetermined loa conditions in the circuit, of means for subsequently tripping the other interrupter at the zero value of the current wave in the circuit.

5. The combination with an alternatingcurrent circuit, of means for producing a voltage drop therein, a resonant circuit connected so that said voltage drop is impressed thereon, means for inductively deriving an electromotive force from said main circuit, means for superposing said electromotive force upon the voltage across one of the members of said resonant circuit, whereby the wave form of said voltage is modified, and means for utilizing the resultant wave.

6. The combination with an alternatingcurrent circuit, of means for producing a voltage drop therein, a resonant circuit connected so that said voltage drop is impressed thereon, means for inductively deriving an impulse electromotive force from said main circuit, means for superposing said impulse electromotive force upon the voltage across one of the members of said resonant circuit, whereby the wave form of said voltage is modified, and means for utilizing the resultant wave.

7. In an electric circuit, the combination age wave across one element of the resonant circuit under predetermined conditions.

9. In an electric circuit, the combination with a circuit interrupter, a trip coil therefor, and a series-resonant circuit operatively connected between the electric circuit and the trip coil, of an inductive means connected in the circuit for peaking the voltage wave across one element of the resonant circuit at its maximum value.

10. In an electric circuit, the combination with an electro-responsive device, a spark gap connected in series therewith and a series-resonant circuit connected between the electric circuit and the circuit comprising the electro-responsive device, of a transformer connected between the electric circuit and the circuit comprising the electro responsive device to peak the voltage wave across the circuit comprising the electro-responsive device at its maximum value.

11. In an electric circuit, the combination with a circuit interrupter, a trip coil therefor, a spark gap connected in series with the trip coil, and a series-resonant circuit connected between the trip coil and the electric circuit, of means connected between the circuit and the spark gap to cause the spark gap to break down only when the current wave traversing the circuit passes through its zero value.

12. In an electric circuit, the combination with a circuit interrupter, a trip coil therefor, a spark gap connected in series with the trip coil, and a seriesresonant circuit connected between the trip coil and the electric circuit, of a normally saturated transformer connected between the circuit and the spark gap to cause the spark gap to break down only when the current wave traversing the circuit passes through its zero value.

13. In an electric circuit, the combination with a main circuit interrupter, of an auxiliary circuit comprising a circuit interrupter and a current-limiting means connected in shunt relation to the main interrupter, and means for tripping the auxiliary circuit interrupter at the zero value of the current wave traversing the same after the main interrupter is opened.

In testimony whereof, I have hereunto subscribed my name this 27 th day of June,

LEWIS W. CHUBB.

cm or this potent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, D. G. 

